It came back and worked flawlessly for four months, and then jammed again. Luckily the camera came with a twelve-month warranty (as a consequence of having paid top dollar for it at a major Sydney camera store), so all I had to do was send the camera back to have it repaired, for no additional cost. When I bought a 1964 M3 in June 2003, the shutter/ wind-on mechanism jammed after only seven hours (!) My own experience will be instructive here. If OTOH you are forking out over $US 1000 for a mint/ collector M3, then it would be wise to insist on some kind of warranty as well. If it's just a "beater" for a couple of hundred dollars, then factor in the risk of failure into the low price. Obviously a lot depends on how much you're willing to pay. If you purchase with a warranty then at least you'll have some recourse when your new M3 arrives DOA. Let's face it, these things are over forty years old and are pretty much antiques. If however the eyelets are small and round, then it's a later model made in the 1960s. How can you quickly distinguish a later model M3 from an earlier one? Easy - look at its "ears": if the strap eyelets look like tear-drops, then it's an older model. It shouldn't cost more than $US 800, even less maybe, especially since Leica MP's now soak up those who would have gone for the M3 earlier on. My advice is to get a beater #920K (or later) single-stroke with a clean VF.
Single-stroke models cost more than double-stroke, serial numbers above 1 million attract a premium, while above #1.1M lands you in "sky's the limit" collector territory. The closer you get to 1966, the more you can expect to pay. So you never imagined how complicated an all-mechanical rangefinder camera can be, eh? In April 2002 Roberto Watson-Garcia gathered together a dozen photographs of the scores of parts required to make an M3. These cameras, despite being forty-plus years old, aren't just for collectors or camera-fondlers either - see this May 2003 discussion about using an M3 for everyday shooting:
Released in 1954 and discontinued in 1966, the Leica M3 is to date the most successful M model, with over 220 000 sold. Leica M3 - the original M rangefinder Introduction